Most EVs have transmissions, they’re just usually single-speed. They have to adjust the RPM of the electric motor to a speed usable by the wheels.

Some have two-speed gearboxes, like the Porsche Taycan. This is needed because EV motors produce full torque at 0RPM and it stays there as the power increases, but eventually you reach a point where the power plateaus and the torque falls off. If you want more power at high speeds, you have to use a second gear.